1. Field of the Invention
The present invention relates to a laser processing device.
2. Description of Related Art
Conventionally, there is known a laser marking device for two-dimensionally scanning an object (hereinafter referred to as a workpiece) with laser light and thus providing marking for the workpiece in a desired manner (e.g., JP 2008-62258 A). Such a laser marking device includes an oscillator for amplifying excitation light to generate a laser beam.
In the oscillator described in JP 2008-62258 A, a solid such as YAG (yttrium aluminum garnet) or YVO4 (yttrium vanadate) is used as a laser medium.
A gas such as CO2 (carbon dioxide) may also be used as a laser medium of the oscillator. A laser marking device having an oscillator using a solid-state laser medium has become widely used, as its oscillator is small in size and provides high output power.
In recent years, in the fields of laser marking devices, there is a demand for higher output power for laser light used in marking, in order to provide marking for a large number of workpieces in a short period of time (reduction of takt time).
In order to achieve higher output power for laser light, it is conceivable, for example, to provide an amplifier including a laser medium after the oscillator described above, and amplify laser light generated by the oscillator by the amplifier. In this case, both of the two laser media of the oscillator and the amplifier have to be excited. Therefore, it is necessary to increase output power of an excitation light source for exciting these two laser media.
In the laser marking device described in JP 2008-62258 A, an LD (laser diode) array having a plurality of emitters (light emitting spots) is used as an excitation light source. However, as the number of the emitters in the LD array is limited, there is also a limitation in increasing output power of the excitation light source to be higher. Further, the LD array is inherently configured such that the plurality of emitters are adjacent to each other. Accordingly, radiation performance of the LD array is poor. Therefore, when the density of the disposed emitters and the number of the emitters are increased, heat generated during driving makes life duration of the LD array shorter.